Parasites: general concepts and ectoparasites

Question 1

Facultative parasite

Answer 1

organism that may become a parasite, but does not require a host for completion of its life cycle.

Question 2

Example of facultative parasites

Answer 2

occur among many species of fungi:
- Blastomyces dermatitidis
- Blastomycosis

Question 3

Opportunistic infection

Answer 3

infection caused by pathogens (bacteria, viruses, fungi or protozoa) that take advantage of an opportunity not normally available, such as:

• host with weakened immune system
• breached integumentary barriers
• altered microbiota

Question 4

Parasitism

Answer 4

when an organism for all or part of its life, derives at least some, but not often all of its food from a living organism of another species (Host), usually living in or on the body or cells of the host, which is usually harmed to some extent by the association.

• ONE WHO EATS AT ANOTHER’S TABLE

Question 5

Ectoparasite

Answer 5

live on the outside of the host

Question 6

Endoparasite

Answer 6

live on the inside of the host

Question 7

Epibiosis

Answer 7

any relationship between two organisms in which one grows on the other but is not parasitic on it

Question 8

Phoresis

Answer 8

is a non-permanent, commensalistic interaction in which one organism attaches itself to another (the host) solely for the purpose of travel.

Question 9

Epibiosis and phoresis

Answer 9

• The act of being carried
• In this case the organism or symbionts are nutritionally independent of each other and have a facultative association ( non-obligatory).

Question 10

Commensalism

Answer 10

• Latin com mensa meaning “sharing a table”
• this occur when a smaller symbiont, the commensal, feeds on the food available in or on the surface of the host, for whom it is unusable or unwanted, while the host neither benefits nor is harmed.

Question 11

Ht - x —> X

Answer 11

Parasitism

Question 12

Ht+- 0 (- x)

Answer 12

Commensalism

Question 13

Ht + Y

Answer 13

Mutualism
(symbiosis - long-term)

Question 14

Ht

Answer 14

Host table complex (food available)

Question 15

Helminths

Answer 15

• parasitic worms, large and multicellular
• includes a number a of phyla, many which are unrelated (phylogenetically) but they have superficial similarities:
• They are vermiform or “worm-like” in form

Question 16

Phyla in Helminths

Answer 16

• Phylum Nematoda (roundworms)
• Phylum Platyhelminthes (flatworms)
• Phylum Acanthocephala (thorny-headed worms)
• Phylum Annelida (segmented worms) not parasites (leeches)

Question 17

Classes of the Phylum Platyhelminthes

Answer 17

• Class Cestoda (tapeworm)
• Class Trematoda (flukes: endoparasites)
• Class Monogenea (skin flukes: ectoparasites)
• Class Turbellaria (free-living flatworms, some parasitic forms)

Question 18

Parasites of veterinary importance

Answer 18

• Helminths
• Kingdom Protozoa (Protist)
• Kingdom of Fungi
• Kingdom Animalia

Question 19

Phylum of Kingdom of Protozoa (Protist)

Answer 19

• Phylum Mastigophora (flagellates)
• Phylum Apicomplexa
• Phylum Ciliophora (ciliates)

Question 20

Phylum of Kingdom of Animalia

Answer 20

• Phylum Arthropoda (insects/arachnids, copepods)
• Phylum Cnidaria (Myxozoa)

Question 21

Parasites

Answer 21

• Live in or on the host
• Smaller than their host
• Parasites reduce host biological fitness to some extend (pathogenicity/virulence)
• Typically don’t kill their host
• Reproduce at a faster rate than their host

Question 22

Parasites use host for survival

EXAMPLES

Answer 22

• Food
• Water
• Heat
• Habitat
• Transmission

Question 23

Mode of infection

Answer 23

• Oral
• Skin penetration
  -Injection
• Transplacental (vertical transmission)

Question 24

examples of oral mode of infection

Answer 24

• Spore in environment
• Oocyst/eggs in environment
• Larvae in environment
• Larvae in intermediate host, paratenic host
• Cyst in other host
• Larvae in milk

Question 25

Types of host

Answer 25

- Definitive host - Intermediate host (IH) - Paratenic host (PH) or transport host - Aberrant or abnormal host - Dead-end or incidental host

Question 26

Intermediate host (IH)

Answer 26

- Required - serves as a temporary but necessary host for continued development of essential life stages

Question 27

Paratenic host (PH) or transport host

Answer 27

NON-REQUIRED transport "intermediate" host in which no development of the parasite occurs

Question 28

Aberrant or abnormal host

Answer 28

- Host not usually used by the parasite - Development slow or incomplete

Question 29

Dead-end or incidental host

Answer 29

An "intermediate" host that generally does not allow transmission to the definitive host , thereby preventing the parasite from completing its development

Question 30

Direct life cycle

Answer 30

- only one host required to complete the life cycle - stages in this host and the environment - Host specific or broad host spectrum (non-specific) - Definitive host (DH) - parasites that (sexually) reproduce without an intermediate host have direct life cycle

Question 31

Definitive host

Answer 31

where sexual reproduction takes place

Question 32

Indirect life cycle

Answer 32

- two or more host required to complete the life cycle - Host specific or broad host spectrum (non-specific) - Final Host (FH): sexual reproduction (DH) - Intermediate host (IH) - Involves stages in the hosts and the environment

Question 33

Sexual reproduction

Answer 33

- Genetic diversity - Longer life cycle - Must have at least 2 parasites (M & F)

Question 34

Asexual reproduction

Answer 34

- Lack of genetic diversity - Short life cycle - One is enough

Question 35

Benefits the parasite gains from the host

Answer 35

- Survival: heat, food, water, habitat - Food: blood, mucosal lining etc. - Transmission or maturation / reproduction - Arrested development/ hypobiotic stage

Question 36

Hypobiosis

Answer 36

- A state of reduced metabolic activity - term most often used for arrested development that has a seasonal basis (nematodes). Can also be caused by host immune responses and an overcrowding effect, high numbers of adults inhibit larvae

Question 37

Habitat and food: Where in the host?

Answer 37

- Predilection site - Aberrant site

Question 38

Predilection site

Answer 38

- preferred site in or on the host - food sources, able to avoid immune systems (for at least some time period) - Feeding and location related to pathology

Question 39

Aberrant site

Answer 39

site in or on a host which is not a normal location

Question 40

Complex life cycle

Question 41

trophic transmission